The present invention relates to a liquid crystal display (LCD) panel unit for use in a LCD device and, more particularly, to the structure of a LCD panel unit having a shield metallic film. The present invention also relates to a method for fabricating the LCD panel unit.
Active matrix LCD device is increasingly used for a variety of applications such as personal computer and mobile communication system. The LCD device generally includes a LCD panel unit for defining a plurality of LCD pixels and a pair of drive units (horizontal driver and vertical driver) implemented as drive ICs for driving the LCD pixels.
Patent publication JP-A-10-228029 proposes a LCD panel unit, such as shown in FIG. 1A as a front view thereof. FIG. 1B is a sectional view taken along line Axe2x80x94A in FIG. 1A for showing the detailed structure of the TFT panel in the LCD panel unit. In FIG. 1B, the TFT panel includes panel terminals for gate lines and drain lines generally implemented by a metallic film 733 and an ITO (Indium-Tin-Oxide) film 732 for connection to external terminals (or TCP leads) of the drive IC (TCP). The TFT panel further includes a protrusion including a second metallic film 735 having a lower resistance compared to the first metallic film 733 and connected to the first metallic film 733 through a via-hole formed in the ITO film 732 and an overcoat film 734 covering the second metallic film 735 for protection thereof against corrosion. A slit 737 is formed in the first metallic film 733 of the panel terminal along the longitudinal direction of the stopper 738 for allowing inspection to assure suitable connection of the panel terminal to the TCP lead of the drive IC.
FIG. 2 shows the step of connection of the panel terminal shown in FIGS. 1A and 1B to the TCP lead, wherein an insulator film 736 mounting thereon TCP leads 730 of the drive IC is depicted as overlying the TFT panel. The TCP leads 730 are bonded to the ITO film 732 of the panel terminals by using a thermal-press technique and anisotropic conductive film (ACF). In the conventional technique, the TCP lead 730 is disposed to oppose the first metallic film 733 and not to oppose the second metallic film 735 of the panel terminals.
The state of the connection of the TCP lead 730 to the panel terminal can be observed at the edge of the TCP lead 730 through the slit 737 formed in the first metallic film 733 by observation from the rear of the TFT panel (or from the bottom of the figure), so long as the TCP lead 730 is positioned at a suitable location relative to the TFT panel.
The relative location is such that if the location of the TCP lead 730 of the drive IC is deviated toward left from the design position during connection for the drive IC, the TCP lead 730 cannot be observed through the slit 737 during or after the connection. On the other hand, if the location of the TCP lead 730 of the drive IC is deviated toward right, the TCP lead 730 can be observed through the entire width of the slit 737.
The LCD device described in the above publication has a disadvantage in that observation of the TCP lead 730, such as by human eyes, is difficult unless the terminal pitch of the TCP leads 730 and the width of the silt 737 is sufficiently large. The observation by human eyes does not in fact afford an accurate judgement as to whether the TCP lead 730 of the drive IC is positioned at a suitable location.
More specifically, the accuracy of the observation by human eyes depends on the contrast of the light intensity caused by the absence or presence of shielding of the passing light by the TCP lead 730. In this respect, deviation of the drive IC toward right can be effectively judged by simply determining an absence or presence of the light passing through the slit 737. On the other hand, deviation of the TCP lead 730 toward left cannot be effectively judged because the judgement must distinguish a difference between the light intensities of the passing light. This situation will not be improved even if two slits are provided for respective edges of the TCP lead 730.
Thus, the observation through the slit 737 necessitates a specific inspection step by using a microscope or a CCD camera. This raises the number of steps for the manufacture of the LCD device and the costs for the fabrication facility, both of which raise the costs of the final products.
In addition, even if the judgement is correct, it is difficult to conduct the repair of the TCP leads 730, wherein the TCP leads 730 positioned at wrong locations are replaced by new TCP leads or shifted toward the correct location after removing the ACF. This difficulty is especially caused by the second metallic film 735 and the overcoat film 734 protruding from the ITO film 732 and thus liable to peel-off during removal of ACF residual in the repair. The peel-off of the second metallic film increases the resistance of the panel terminal, which is undesirable.
In view of the above, it is an object of the present invention to provide a LCD panel unit for a LCD device, including panel terminals having slits therein for effectively allowing observation of the connection between the panel terminals and TCP leads of the drive unit.
It is another object of the present invention to provide a method for fabricating such a LCD panel unit.
It is another object of the present invention to provide a method for manufacturing the LCD device as described above.
The present invention provides a LCD panel unit for use in a LCD device, comprising a pair of glass substrates sandwiching therebetween liquid crystal for defining an array of LCD pixels, a plurality of first signal lines each disposed for a corresponding row of the LCD pixels, a plurality of second signal lines each disposed for a corresponding column of the LCD pixels, each of the first signal lines and the second signal lines having an panel terminal to be connected to a lead of a drive unit for the LCD panel unit, at least one of the panel terminals having a slit section therein for allowing light to pass therethrough, the slit section including at least one slit having a center substantially aligned with a center of the panel terminal, as viewed in a width direction of the slit normal to an extending direction of a corresponding one of the signal lines.
The present invention also provides a method for fabricating a LCD panel comprising the steps of forming a first glass panel having an array of LCD pixels and signal lines for driving the LCD pixels, forming a second glass panel, bonding the first glass panel and the second glass panel together to form a LCD panel unit, the first glass panel forming step includes the step of forming a slit section including at least one slit in a panel terminal of each of the signal lines, the slit having a center substantially aligned with a center of the terminal.
In accordance with the present invention, the slit formed in the panel terminal of the LCD panel unit affords an effective inspection as to whether or not the TCP lead is aligned with the panel terminal, because the alignment can be assured substantially by detecting an absence or presence of the light passing through the slit.